SMTP Service Extension for Indicating the Responsible Submitter of an E-Mail Message
spam
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This memo defines an extension to the Simple Mail Transfer Protocol (SMTP) service that allows an SMTP client to specify the responsible submitter of an e-mail message. The responsible submitter is the e-mail address of the entity most recently responsible for introducing a message into the transport stream. This extension helps receiving e-mail servers efficiently determine whether the SMTP client is authorized to transmit mail on behalf of the responsible submitter's domain. This memo defines an Experimental Protocol for the Internet community.